1. Field of the Invention
This invention relates to nondestructive methods developed for measuring the thickness or variation in thickness of a region within a material microstructure and, more specifically, to a multi-step method of measuring the thickness or variation in thickness of one or more region in ultra-hard polycrystalline constructions.
2. Background of the Invention
The formation of constructions having a material microstructure made up or two or more different layers or regions of materials is well known. Such constructions are intentionally engineered in this fashion to provide a desired mix of physical, mechanical and/or thermal properties within the material microstructure, making it better equipped to handle a particular end use application. In order to provide such desired properties in a predictable and consistent manner, the thickness or variation of thickness of each engineered region must be controlled.
It is, therefore, necessary that the thickness of each such region within the construction be measured for the purpose of both controlling the process that is used to make the construction, to ensure its consistency and for controlling the quality or ability of the construction to perform as expected. Methods useful for measuring the thickness or variation in the thickness of a region within a material construction will vary depending on the nature of the construction. For material constructions used in tooling, wear, and cutting applications provided in the form of an ultra-hard polycrystalline material, e.g., comprising polycrystalline diamond, a useful method for measuring the thickness or variation of thickness of one or more region within the construction is by destructive method or destructive testing.
Destructive testing requires that the construction itself be cut or otherwise treated in a manner that physically exposes the different regions therein so that they can be measured by visual inspection. In an example embodiment, where the construction is one comprising an ultrahard polycrystalline material such as diamond or cubic boron nitride, the construction itself is cut, e.g., in half, so that the different regions forming the construction can be viewed visually for purposes of measuring the thickness or variation of thickness of the regions. In an example embodiment, such visual indication is made with the assistance of a magnifying device such as a microscope, e.g., a scanning electron microscope.
While such destructive test method is useful for determining the thickness or variation of thickness within a construction, it is time consuming in that after the part is cut it must usually be further prepared by grinding, polishing or the like, then mounted for microscopic evaluation, and the microscopic evaluation must be taken over a number of different points to gather sufficient data to arrive at a numerical value, e.g., an average region thickness throughout the part. Further, the use of such destructive test method is expensive, and results in the parts that are measured being destroyed, thereby adversely impacting the economics of making the parts.
It is, therefore, desired that a method be developed that is capable of measuring the thickness or variation of thickness within a region of a material construction, e.g., an ultra-hard polycrystalline construction, in a manner that is not destructive. It is further desired that such a method be capable of providing such a desired measurement in a manner that has a consistent degree of accuracy. It is further desired that the method be capable of providing an indication of the region thickness at different locations within the construction, and enable efficient testing on a large-scale production basis.